The goals of this proposal are to elucidate the function(s) of the short-chain and medium-chain carnitine acyltransferases that occur in mitochondria, endoplasmic reticulum and peroxisomes of tissues such as liver. The working hypothesis for this research is that carnitine is involved in branched-chain amino acid metabolism. Major efforts will be made to characterize the systems that use and produce branched-chain acylcarnitines. The effect of various induced physiological states, i.e. alloxan diabetes, clofibrate treatment, and long term fasting on the levels of water-soluble aliphatic acylcarnitines in liver, muscle and other tissues will be investigated. The possible conversion of leucine, valine, and isoleucine to branched-chain acylcarnitines will be investigated. Carnitine octanyltransferase activity in beef heart mitochondria will be isolated and characterized. Branched-chain carnitine acyltransferase(s) will also be investigated. The subcellular distribution in liver of the branched-chain carnitine acyltransferases, the alpha keto acid dehydrogenases that use branched-chain keto acids as substrates and the branched-chain amino acid transaminases will be determined. Identification and characterization of the short-chain water-soluble acylcarnitines that occur in tissues will be continued.